Ectopic adrenocorticotropic hormone secretion (EAS) from the pancreatic neuroendocrine tumour (PNET) is rare, aggressive, and challenging to treat. We hereby present a rare case of EAS from PNET presenting with Cushing syndrome diagnosed with endoscopic ultrasound-guided fine-needle aspiration cytology. This case highlights the advanced presentation of EAS from PNET with poor clinical correlation of hypercortisolism and the grade of PNET.